1. Technical Field
The present invention relates to a detection apparatus, a wafer, and an electronic device.
2. Related Art
As a conventional method of detecting process variation in MOSFETs, a method using a ring oscillator (see Non-Patent Document 1) and a method using a sense amplifier (see Non-Patent Document 2) are known.    Non-Patent Document 1: I. A. K. M. Mahfuzil, H. Onodera, “On-chip detection of process shift & process spread for silicon debugging and model-hardware correlation,” ATS2012.    Non-Patent Document 2: S. Mukhopadhyay, K. Kim, K. A. Jenkins, C-T. Chuand, K. Roy, “Statistical Characterization and On-Chip Measurement Methods for Local Random Variability of a Process Using Sense-Amplifier-Based Test Structure,” ISSCC 2007, February 2007.
The method of Document 1 includes measuring threshold voltages of an nMOSFET and a pMOSFET forming a ring oscillator, based on variation in the oscillation frequency of the ring oscillator. However, since an AC signal is being measured, the measurement is easily affected by jitter and there is a non-linear relationship between the threshold voltage and the oscillation frequency, and therefore it is difficult to improve the measurement accuracy. Furthermore, in the method of Document 2, information is exchanged through the scan chain, and therefore the measurement speed is low.